Pre-approved ADU plans, also called permit-ready or standard plans, are building plans for an accessory dwelling unit that a city or county has already reviewed for code compliance. In Orange County, the County (for unincorporated areas) and 11 cities had plan sets posted when we checked in October 2026: Anaheim, Santa Ana, Garden Grove, Westminster, Huntington Beach, Newport Beach, Mission Viejo, Laguna Hills, Laguna Niguel, Los Alamitos and San Juan Capistrano.
Many other cities have a program but had no plans listed yet, and La Habra and Aliso Viejo accept plans pre-approved by other agencies. Using one can cut design costs and shorten review, since state law gives a city 30 days to decide a complete application for a detached ADU that uses one. It does not cover your site plan, utility connections, soils, fire sprinklers where required, fees or HOA approval.
For general ADU rules, lender treatment and property taxes, see our guide to buying a home with an ADU in Orange County.
What state law requires
Assembly Bill 1332 (2023) added Government Code section 65852.27, which required every city and county, including charter cities, to have a program for preapproving ADU plans by January 1, 2025. The agency must accept plans from anyone who submits them, may charge the same permitting fees it would for an ADU of the same size, and must post approved plans on its website. It may also admit plans preapproved by other agencies in California, but that part is optional.
The time savings come from subdivision (b). For a detached ADU that uses a plan the agency preapproved within the current triennial building code cycle, or a plan identical to one it approved in that cycle, the agency must approve or deny a complete application within 30 days. Other ADU permits get 60 days from a complete application when a home already exists on the lot, under Government Code section 66317.
The section was last amended in 2024 by SB 477, which updated its cross-references. We found no amendment taking effect in 2026 or on January 1, 2027.
Three kinds of pre-approved ADU programs
- Plans the agency offers directly. The County, Anaheim, Santa Ana, Garden Grove, Westminster, Huntington Beach, Newport Beach, Laguna Hills and Laguna Niguel post plan sets for download. Anaheim lists its plans as free, Garden Grove and Huntington Beach say theirs are free of charge, and Laguna Niguel says its plans can be downloaded for free.
- Designer-owned plans. Mission Viejo, Los Alamitos, Irvine, Cypress, Seal Beach, Villa Park, Yorba Linda and others list, or plan to list, plans that architects submitted and still own. You buy or license the plan from the designer, who sets the price.
- Prefabricated units. San Juan Capistrano's pre-approved plans are for a studio from the prefabricated home maker BOXABL.
- Plans from another agency. La Habra says plans preapproved by the County of San Diego are acceptable for permitting there, and Aliso Viejo accepts pre-approved plans from the County of San Diego and the City of Newport Beach.
Westminster's page makes the key point: its plans are preapproved but "not pre-permitted." You still file a complete permit application, and staff still review how the unit fits your lot.
How a pre-approved plan changes cost and timing
Design cost. A pre-approved plan replaces the drawings for the unit itself, not the site-specific work. Garden Grove's free plans are architectural only, so the applicant supplies a site plan, Title 24 energy documents, structural plans and calculations. Mission Viejo describes its pre-approved plans as about 70% complete.
Permit fees. Plan check, permit and impact fees generally still apply. Lake Forest states that fees are the same for all ADU applicants whether or not they use a pre-approved plan. San Clemente is one exception we found: for projects with no changes to a pre-approved plan, plan review is 25% of the original plan review fee (as published, checked October 2026).
Review time. Some cities publish targets faster than the 30-day deadline. Santa Ana says a complete, code-compliant over-the-counter submittal may be approved in as little as one day, and Lake Forest and Mission Viejo list 10 business days for a first plan check. Anaheim says its eligibility screening can take a few weeks, after which qualifying single-family lots can complete ADU Express review within one to three days. Clocks start only once your application is complete, and construction time does not change.
Less flexibility. Huntington Beach says modifications or deviations from its plan are not allowed, and La Habra says the San Diego County plans cannot be modified. A custom layout goes through standard review.
What a pre-approved plan does not cover
Every program we read still requires site-specific work:
- Site plan. The County, Santa Ana, Westminster, Garden Grove, Laguna Hills and Brea all require a site plan for your specific property.
- Utility connections. The County's checklist asks for the distance from water, gas and electric connections to the ADU and whether new meters are proposed. Costa Mesa lists a sewer permit and a water improvement plan, and Anaheim asks for a copy of your utility "meter spot."
- Soils and grading. Huntington Beach's plan is intended for flat lots without highly expansive or liquefiable soils. Laguna Hills lists a soils report in its required package, Brea may require one, Costa Mesa requires one for ADUs over 800 square feet, and Newport Beach requires a geotechnical report for additions over 1,000 square feet (500 in liquefaction or landslide areas).
- Fire sprinklers. The County requires them when the main house has sprinklers or the ADU will be within five feet of a property line. Newport Beach and Huntington Beach tie the requirement to the main house, and Costa Mesa to a fire hose pull distance over 150 feet.
- Energy and solar. Title 24 energy documents are site specific, and the County requires a solar plan from a third-party installer. Los Alamitos requires a separate solar permit, and San Juan Capistrano requires separate roof, foundation and solar permits.
- School and impact fees. Santa Ana collects permit, capacity and impact fees before issuing permits, with school district fees paid at the district. Placentia says plan check and development impact fees still apply.
- HOA approval. Civil Code section 4751 voids CC&R provisions that prohibit or unreasonably restrict ADUs on single-family lots but allows reasonable restrictions, so HOA review is a separate step from the city permit.
Eligibility can also rule a lot out. Santa Ana excludes flood zones A and AE and certain historic districts, Garden Grove excludes flood Zone A, Brea excludes methane and flood zones, and San Clemente excludes flood zones and historic properties. Huntington Beach and San Clemente note that coastal zone lots may also need coastal approval.
Permit-ready ADU plans in Orange County, city by city
We checked each city's official website on October 30 and 31, 2026. "Not found" means we did not find a program on the city's website as of October 2026; ask the planning counter. Programs change often, so confirm with the city.
County of Orange (unincorporated areas)
OC Development Services posts six pre-approved plans for new detached ADUs: a 393-square-foot studio, a 558-square-foot one-bedroom, two-bedroom plans of 748 and 800 square feet, and three-bedroom plans of 972 and 1,200 square feet. They apply where the County issues permits, outside city limits. The page says the plans reflect the 2022 California Building Code and are being updated to the 2025 code. Applicants submit a complete package through the County's online portal, including a site plan, a solar plan, a plan preparation checklist and a hold harmless statement.
North Orange County
- [Anaheim](/areas/anaheim/): The Pre-Approved Plan Catalogue lists four free plans for the city's ADU Express process: a 224-square-foot studio, a 499-square-foot one-bedroom, a 990-square-foot two-bedroom and a 1,199-square-foot three-bedroom. Vendors can apply to add plans.
- Brea: The pre-approved plan program page invites designers and builders to submit plans and says approved designers will be listed, but it listed none when we checked.
- Buena Park: Not found.
- Cypress: The Preapproved ADU Program page invites design professionals to submit plans, but its catalog showed no submissions.
- Fullerton: Not found.
- La Habra: The city's ADU page says plans preapproved by the County of San Diego are acceptable for permitting, with La Habra-specific information added and no modifications.
- La Palma: Not found. The City Council has a public hearing set for November 10, 2026 on an ordinance amending its ADU rules.
- [Los Alamitos](/areas/los-alamitos/): The city's pre-approved ADU plans page lists two one-story, all-electric plans by Long Beach Designers: a 563-square-foot one-bedroom, one-bath unit and an 876-square-foot two-bedroom, two-bath unit with a 132-square-foot patio cover. The drawings belong to the architect, so you get the plan from the designer before you apply.
- Placentia: The city's pre-reviewed ADU program accepts prototype plans, but the page says the city has not taken in any submittals for preapproval yet.
- Stanton: Not found.
- Yorba Linda: The Preapproved ADU Program page says the city is in the first phase of soliciting designs. Designers keep the copyright, and homeowners contract with them directly.
Central Orange County
- Fountain Valley: Not found.
- [Garden Grove](/areas/garden-grove/): ADU Go offers four city-owned plans free of charge: a 447-square-foot studio, a 630-square-foot one-bedroom, a 750-square-foot two-bedroom and a 1,000-square-foot three-bedroom. Plans from private architects, at a fee the architect sets, were listed as coming soon.
- [Irvine](/areas/irvine/): The Pre-Approved ADU Plans Program page describes designer-owned standard plans purchased from the plan owner, but its plan list read "Coming soon."
- Orange: Not found.
- [Santa Ana](/areas/santa-ana/): The city's pre-approved plans for detached ADUs include a 399-square-foot studio and a 499-square-foot one-bedroom in ranch, Spanish or traditional styles, a 625-square-foot contemporary one-bedroom, 677-square-foot craftsman and Spanish one-bedrooms, and a 749-square-foot contemporary two-bedroom.
- [Tustin](/areas/tustin/): Not found.
- Villa Park: Its program announcement invites design professionals to submit plans and says the city is in the first phase of soliciting designs.
- [Westminster](/areas/westminster/): The standard plan program offers six detached floor plans from 748 to 1,198 square feet (net, measured from interior walls), with two to four bedrooms and three roof options each, for 18 combinations.
Coastal Orange County
- Costa Mesa: The Pre-Approved ADU Program pre-approves designs submitted by architects, but its plan directory was marked coming soon.
- [Huntington Beach](/areas/huntington-beach/): The city's ADU page offers one free plan, a one-story, 490-square-foot detached ADU with one bedroom and one bath, in California Ranch, Bungalow or Spanish Colonial style.
- Laguna Beach: Not found.
- [Newport Beach](/areas/newport-beach/): The city's ADU site offers five ADU Standard Plans: a 448-square-foot studio, a 504-square-foot studio and a 672-square-foot one-bedroom, each in three styles, plus one- and two-car garage conversions. Designers can ask to add plans to the catalog.
- Seal Beach: The ADU page invites design professionals to submit plans, but its catalog showed no submissions.
South Orange County
- [Aliso Viejo](/areas/aliso-viejo/): The city's ADU page says pre-approved plans from the County of San Diego and the City of Newport Beach are acceptable for plan check and permitting, with project-specific information added.
- Dana Point: The city's ADU permit page says it currently has no pre-approved ADU plans and that designers, owners and applicants may submit drawings for pre-approval review.
- [Laguna Hills](/areas/laguna-hills/): The city's pre-approved ADU plans page offers three plan sets for download: a 389-square-foot studio, a 499-square-foot one-bedroom and a 789-square-foot two-bedroom. The package also needs a site plan, an updated Title 24 report, a hold harmless agreement, an Orange County Fire Authority form, a city questionnaire and a soils report.
- [Laguna Niguel](/areas/laguna-niguel/): The city's Pre-Approved ADU Program offers three free plan sets, each with one bath and in California Ranch, Modern Farmhouse and Mediterranean styles: a 350-square-foot studio, a 532-square-foot one-bedroom and a 757-square-foot two-bedroom. The city says only the site plan and the ADU's location need review.
- Laguna Woods: Not found.
- Lake Forest: The city's program document, dated October 15, 2026, places no restrictions on who may submit plans, and its plan table had no entries yet. It promises a first plan review within 10 business days and a decision within 30 days of a complete application.
- [Mission Viejo](/areas/mission-viejo/): The program linked from the city's housing page lists one designer-owned plan, an 800-square-foot detached ADU with one bedroom and two baths by Migliozzi Architecture. Homeowners contract with the designer, and plan check fees apply.
- Rancho Santa Margarita: Not found.
- San Clemente: The program document lets builders, architects, engineers and designers offer pre-approved plans, but we did not find a published list of approved plans.
- [San Juan Capistrano](/areas/san-juan-capistrano/): The city's ADU page offers pre-approved plans for a BOXABL prefabricated studio casita for single-family lots. Applicants still go through the standard ADU permit process, with separate roof, foundation and solar permits.
If your city has no plans posted: what to ask
State law required every city to have a preapproval program by January 1, 2025, even if no plans are posted yet. Before you hire a designer, ask the planning counter:
- Where are the city's preapproved plans under Government Code section 65852.27 listed?
- Will the city admit plans preapproved by another California agency, such as the County of Orange? State law allows this but does not require it.
- Is the property eligible, given flood zones, historic districts, hillside or fire hazard areas and the coastal zone?
- Which site-specific documents are required, and can fire sprinklers or solar be deferred submittals?
- Which fees apply, and are any reduced for a pre-approved plan?
- How long will review take once the application is complete?
This is general information, not legal advice. Plan programs, fees and eligibility rules change, so confirm the details for a specific property with the city's planning and building department.
How Remark Homes can help
If you might add an ADU after you buy, a posted plan lets you compare a footprint with the backyard before you make an offer. We help Orange County buyers check setbacks, utilities, hazard zones, HOA rules and the city's program during the contingency period. Learn more about buying with Remark Homes, or get started when you are ready to tour homes.
Frequently asked questions
What is a permit-ready ADU plan?
It is a set of ADU building plans that a city or county has already reviewed for code compliance. You still submit a permit application with a site plan and other site-specific documents, and the city reviews how the unit fits your lot.
Are pre-approved ADU plans free in Orange County?
Some are. Anaheim, Garden Grove, Huntington Beach and Laguna Niguel describe their plans as free, while Mission Viejo, Los Alamitos and several other cities use designer-owned plans that you buy or license from the designer. Permit and impact fees still apply either way.
How long does approval take with a pre-approved plan?
State law requires a decision within 30 days of a complete application for a detached ADU that uses a plan the city preapproved in the current building code cycle, compared with 60 days for other ADU permits on lots with an existing home. Some cities publish shorter targets.
Can I use the County's plans inside a city?
The County's plans are for unincorporated areas. State law lets a city admit plans preapproved by other agencies but does not require it; La Habra and Aliso Viejo, for example, accept the County of San Diego's plans. Ask your city before relying on another agency's plan.
Sources
- California Legislative Information: Government Code section 65852.27
- California Legislative Information: Government Code section 66317
- California Legislative Information: Civil Code section 4751
- OC Development Services: Pre-Approved Accessory Dwelling Unit (ADU) Plans
- OC Development Services: Pre-Approved ADU Plans Application Process Guide and Checklist
- City of Santa Ana: Pre-Approved ADU Plan Submittal Process
- City of Huntington Beach: Pre-Approved ADU Program Brochure
- City of Newport Beach: ADU Standard Plan Checklist
- City of Brea: Pre-Approved ADU Plans Program
- City of San Clemente: Pre-Approved ADU Plans Program
